Issue 17, 2019

Characterization of the adsorption site energies and heterogeneous surfaces of porous materials

Abstract

Characterization of the guest–host interactions and the heterogeneity of porous materials is essential across the physical and biological sciences, for example for gas sorption and separation, pollutant removal from wastewater, biological systems (protein–ligand binding) and molecular recognition materials such as molecularly imprinted polymers. Information about the guest–host interactions can be obtained from calorimetric experiments. Alternatively, more detailed information can be obtained by properly analysing the experimentally acquired adsorption equilibrium data. Adsorption equilibrium is usually interpreted using theoretical adsorption isotherms that correlate with the equilibrium concentration of the adsorbate in the solid phase and in the bulk fluid at a constant temperature. Such theoretical isotherms or expressions can accurately predict the adsorbent efficiency (at equilibrium) as a function of process variables such as the initial adsorbate concentration, adsorbent mass, reactor volume and temperature. Detailed analysis of the adsorption isotherms permits the calculation of the number density of the adsorbent sites, their binding energy for the guest molecules and information about the distribution of adsorption site binding energies. These analyses are discussed in this review. A critical evaluation of the analytical and numerical methods that can characterize the heterogeneity and guest–host interactions involved in terms of discrete or continuous binding site affinity distribution was performed. Critical discussion of the limitations and the advantages of these models is provided. An overview of the experimental techniques that rely on calorimetric and chromatographic principles to experimentally measure the binding energy and characteristic properties of adsorbent surfaces is also included. Finally, the potential use of site energy distribution functions and their potential to provide new information about the binding energy of adsorbents for a specific guest molecule application is discussed.

Graphical abstract: Characterization of the adsorption site energies and heterogeneous surfaces of porous materials

Supplementary files

Article information

Article type
Review Article
Submitted
09 Jan 2019
Accepted
19 Feb 2019
First published
21 Feb 2019

J. Mater. Chem. A, 2019,7, 10104-10137

Characterization of the adsorption site energies and heterogeneous surfaces of porous materials

K. V. Kumar, S. Gadipelli, B. Wood, K. A. Ramisetty, A. A. Stewart, C. A. Howard, D. J. L. Brett and F. Rodriguez-Reinoso, J. Mater. Chem. A, 2019, 7, 10104 DOI: 10.1039/C9TA00287A

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements